When we’ll know restrictions are working

If the recent ramping up of restrictions on people's movements to tame the spread of coronavirus has been effective, we should see an impact in numbers of new infections by around Easter, experts have said.

Last week, state governments began a gradual lockdown banning mass gatherings, closing pubs and restaurants and encouraging people to limit outdoor activities.

In the last few days these restrictions have gone even further, to stage 3, with groups of more than two banned, people told to leave the house only to buy the essentials and for exercise and overseas arrivals quarantined in hotels.

The aim is to slow down community transmission of COVID-19, where the virus jumps from person to person outside family or established groups.

Health Minister Greg Hunt is already cautiously optimistic about Australia's infection numbers and has said the growth in new cases has slowed from 25 to 30 per cent to 9 per cent in a week.

"In these most difficult of times, with these most difficult of measures that none of us had ever dreamt we would ever be involved in, you have risen to the occasion," he said on Sunday.

"We are seeing what I would describe as early promising signs of the curve flattening."

But Mr Hunt said people still needed to social-isolate and keep their distance from one another to keep the numbers down.

More than 4500 cases of coronavirus have been detected across Australia and 20 people have died.

New cases reached a high of 460 on March 28 and had fallen to 314 yesterday, although more than the 270 new cases recorded on Monday.

Cases in New South Wales, the worst affected state, have been on a general downward trajectory since the more than 200 cases recorded on Thursday and Saturday but today's 150 new infections were up from the day before. Other states' numbers have also been erratic.

Around 10 per cent of all Australian cases of coronavirus have come from a single cruise ship - the Ruby Princess, where more than 400 infected passengers were allowed to disembark in Sydney.

Health Minister Greg Hunt has said he is cautiously optimistic about the trend in new infections. Picture: Lukas Coch/AAP

IMPACT IN SEVEN TO 14 DAYS

Paul Glasziou, the director of Bond University's Institute for Evidence-Based Healthcare, said the figures so far had showed isolating arrivals from overseas and banning large gatherings were having an effect.

"Things are actually looking very good," he told the ABC.

Without the measures put in place, Australians cases might be double what we currently have or around 8000 people with COVID-19.

"It means it's taken about seven to 14 days for these new interventions to kick in," Prof Glasziou said.

With the changes introduced on Monday, Australians should be seeing an impact on the number of cases by the end of next week, he added.

That could mean the further restrictions imposed will lead to a further push down in new infections from Monday, April 6 with the full effect by the Easter weekend of April 11- 12.

However, if the numbers don't continue to fall it could be a sign the virus is spreading within the community and a significant number of people are ignoring instructions to socially distance.

Travellers and Australian residents who arrive into the country from overseas are being sent to hotels to spend 14 days in quarantine Picture: Bianca De Marchi/AAP

'NEED TO KEEP BRAKES ON'

On the weekend, Victoria's chief health officer Brett Sutton said that the behaviour of some people "has been really cr*p". His comments came after pictures emerged of sunbathers in groups on St Kilda beach in Melbourne.

"It's hard to see dangers that aren't apparent yet. But with 3000 cases of COVID in Australia (last) week, we're headed to 100,000 in two to three weeks without change."

There are concerns that if Australians become too lulled into complacency about fewer cases, infections could soar again if they fail to social distance.

"We need to keep the brake on as much as possible for at least the next fortnight," Adam Kamradt-Scott, an expert in infectious diseases at the University of Sydney's Centre for International Security Studies, told SBS.

"Think about your parents, think about your grandparents, and continue to comply with the measures so you don't have to be attending their funerals."

Two Australian Border Force officers - one from NSW and one from Queensland - are among the most recent people to have become infected. Clusters of coronavirus cases have also been found in the Sydney backpacker haven of Bondi and among baggage handlers at Adelaide Airport.

Following Sunday's national cabinet meeting, Prime Minister Scott Morrison announced new restrictions that have come into place this week.

Gatherings are restricted to two people outside of the household with outdoor gyms, skate parks and playgrounds closed.

Weddings and funerals can take place but with severely limited numbers.

People should now only leave home to buy food and essential items; medical supplies, work or education that cannot be done at home, exercise and for compassionate reasons.

Most shops are allowed to remain open but cafes and restaurants can only do takeaway and delivery.

All overseas arrivals to Australia are now forced into quarantine into hotels in the city where they land. Some states are forcing people who arrive from other states and territories to self isolate for 14 days.